The invention relates to devices for forming grooves in workpieces, especially cylindrical work-pieces.
In construction engineering, as in many other areas of technology, cylindrical workpieces--bolts, for example--are needed that are provided with at least one groove on their peripheries--that is, with a depression imprinted in the workpiece by permanent distortion of the material of the workpiece and preferably extending longitudinally along the workpiece. A typical example of such workpieces in a so-called "slotted pin", which is used as a connecting element.
Devices for forming grooves in workpieces and especially in cylindrical workpieces, are already known. However, constructing the known devices takes a relatively large amount of time and money. Another disadvantage of the known devices is that the tools or tool assemblies that are used have groove cutting edges that wear out relatively quickly and consequently have to be replaced very frequently, thus, the known devices have a relatively short edge life.
The basic task of the invention is to produce a device for making grooves in workpieces which, because of its relatively simple and therefore inexpensive construction, provides the best possible application of power on the workpiece to be grooved, the best possible distribution of forces in the grooving device, and a long edge life.
To accomplish this task, a device constructed in accordance with the invention includes a first tool part having a receiver for the workpiece, at least on lever pivotably mounted on the first tool part, said lever supporting a tool provided with a cutting edge on its side facing the receiver, the lever further having a first bearing or supporting surface on its side opposite the cutting edge against which one end of a clamping edge butts; and a second tool part that is attached to the first tool part so that it can pivot around an axis of the receiver, the second tool part having a second bearing and supporting surface for the clamping bolt on its side that faces the receiver.
The device of the invention is unique in that is has the best possible construction, wherein the forces that arise and must be controlled during the grooving process are concerned; that means, above all, that powerful forces can be controlled and can be generated for the grooving process even though the tools and the device being used are small. It is also possible, with the tools and the device of the size provided, to groove large diameter cylindrical workpieces or workpieces of other shapes. It is also possible to form grooves of considerably greater length, width and/or depth in a workpiece, than is possible with other known tools and devices of the same size.
In the device of the invention, the transmission of power to the grooving lever is accomplished through a clamping bolt, one end of which abuts against the lever or a first bearing and supporting surface thereon, while its other end abuts against a second bearing and supporting surface that is provided on the second tool part. Since the second tool part, in relation to the first tool part, can be pivoted around an axis coinciding with the axis of the workpiece receiver, the clamping bolt acts as a toggle lever. That is, in the initial or normal position of the second tool part, the axis of the clamping bolt is at a slightly oblique angle to a line running radially to the workpiece receiver and through the first bearing and supporting surface. When the second tool part pivots or rotates into its operating position, the longitudinal extension of the clamping bolt coincides or nearly coincides with the axis of that radial line. Thus, in the operating position, in which the cutting edges of the tool assemblies are pressed into the material of the workpiece, the longitudinal extension of the clamping bolt makes a considerably smaller angle with the radial line than in its normal position. As a result, when the second tool part rotates or pivots into the operating position, powerful forces are applied to the lever.
In a preferred embodiment of the device of the invention, the second tool part is annular and is attached to a ring surface of the first tool part that is attached concentrically to the workpiece receiver. As a result, a support for the second tool part emerges that has a large surface and hence is the best possible support. Furthermore, as a result of making the second tool part an annular element, the best possible distribution of power is obtained in that tool part--that is, the second tool part can carry a heavy load because of its annular construction.
In the preferred embodiment of the invention, several levers are distributed around the workpiece receiver and each having at least one tool or tool assembly, with each lever then being operatively connected to the second tool part by a clamping bolt. Several grooves can thus be formed in a workpiece in one working operation. At the same time, the optimum construction, from the point of view of strength, is provided by a device of this type since forces exerted upon the workpiece by the individual tool assemblies in grooving cancel each other out.
It is evident that not only grooves in the literal sense, but also other indentations, can be put into workpieces with the device of the invention, so that the word "groove," when used in connection with the invention, should be understood to mean any kind of indentation.
The phrase "cutting edges", as used herein should be understood to meat not only elongated cutting edges, in the literal sense, but also working surfaces of tools or tool assemblies that come to a point, including cone-shaped working surfaces for impressing conical indentations in to workpieces, for example. The tool having a cutting edge can also be a wheel (a groove wheel) provided with a cutting edge.
To obtain especially favorable conditions for driving the second tool part from its normal position to its operating position and back again to its normal position and also to obtain a steady movement or pivoting of the second tool part that is as noiseless as possible, one end of an operating lever is fastened to the second tool part. The length of the operating lever is at right angles to the axis enclosing the receiver; its other end is hinged to one end of an intermediate lever. The other end of the intermediate lever is provided with a bearing with which a circular-cylindrical eccentric of an eccentric drive meshes. This results in not only the best possible transmission of power to the second tool part, but also in a very steady movement that avoids abrupt acceleration, and thus the device is made to run quietly.
The workpieces that are to receive at least one groove are preferably delivered to the device of the invention in a synchronization, with the movement of the second tool part being synchronized with the delivery of the workpieces in such a way that every time the second tool part is in its normal, or initial, position a new workpiece is moved into the workpiece receiver. The removal of the workpiece that has received at least one groove from the workpiece receiver takes place when the second tool part has returned to its normal, or initial, position. But the removal of the workpiece can also take place or begin when the second tool part has reached its final operating position.
Especially when a wheel (a groove wheel) provided with a cutting edge on its peripheral area is being used as a tool, it is also possible to move the workpiece that is being processed at any one time into the workpiece receiver even before the second tool part has reached its final operating position, in order to produce grooves whose depth increases from one end to the other.
With the device of the invention, individual pinlike or boltlike workpieces can be processed, or a continuous piece of steel wire can be provided with individual grooves and then be divided up into individual workpieces.
The invention is described in greater detail in the following description of a preferred embodiment, with reference to the drawings.